The present invention relates to a drill. More particularly this invention concerns such a drill chuck used on a power drill and constructed to clear itself of any chips or other particles generated by a drilling operation.
A standard drill has a drive unit with a housing having an end wall from which a drive-unit spindle projects along an axis. A chuck body fixed to the spindle and formed with an axially forwardly open tool recess has a plurality of angled guide passages opening forward into the recess. Respective jaws displaceable in the passages are engageable in the recess with a tool. A rear plate mounted on the chuck body axially rearward of the jaws projects transversely of the housing end wall and is formed with a hole communicating with the recess and having an open outer end.
Thus particles that get into the chuck, for instance when drilling overhead when the tool recess is open upward, can work their way back and out of the chuck via the hole through the plate. Unfortunately these particles can then often get into the drive unit, fouling the bearing around the spindle and generally clogging the space between the chuck and the drive unit.
It is therefore an object of the present invention to provide an improved drill.
Another object is the provision of such an improved drill which overcomes the above-given disadvantages, that is which prevents particles from fouling the drive unit.
A drill has according to the invention a drive-unit housing having an end wall, a drive-unit spindle projecting along an axis from the wall, and a chuck body fixed to the spindle, formed with an axially forwardly open tool recess, and formed with a plurality of angled guide passages opening forward into the recess. Respective jaws displaceable in the passages are engageable in the recess with a tool. According to the invention a rear plate mounted on the chuck body axially rearward of the jaws and projecting transversely of and closely axially juxtaposed with the housing end wall is formed with a hole communicating with at least one of the passages and having an outer end radially outside the end wall.
Thus with this system rotation of the chuck will cause particles issuing from the hole to be centrifugally propelled outward, away from the mechanism. Since the hole opens radially outward of the end wall of the housing, it is impossible for particles to get into the drive unit.
According to the invention the end wall is an annular collar centered on the axis and having an annular front end closely axially juxtaposed with the rear plate. It has an axially forwardly tapered outer surface having a front edge lying radially inside an orbit defined by the outer hole end on rotation of the chuck. In this manner the collar outer surface will deflect any particles issuing from the hole radially outward. This outer surface is normally frustoconical to prevent any particles from lodging on it.
The rear plate is formed in accordance with the invention with an axially rearwardly open annular groove receiving the collar front end. More particularly it is formed with an axially rearwardly projecting circular ridge defining an outer flank of the groove. The rear plate is out of direct contact with the collar front end. Thus the interfitting collar and groove form a labyrinth or interference seal that prevents anything from entering the drive unit while still offering no significant resistance to rotation of the chuck on the drive unit.
The plate is formed according to the invention with one such hole for each of the guide passages, each hole communicating with the respective guide passage. Normally there are three passages, each holding a respective jaw, so that there are three angularly equispaced holes communicating with the jaw-guide passages
Each of the holes extends relative to the axis at an acute angle open axially rearward. Thus centrifugal force propels the particles outward away from the drive unit.
The rear plate is formed between the holes with respective radially extending and axially projecting stiffening ribs allowing the groove to be fairly deep without weakening the plate. In addition this rear plate is fixed on the chuck body and has an axially forwardly projecting rim that serves as a grip point for the user of the chuck. Normally a sleeve on the chuck has a cylindrical outer surface level with that of the rim and can be rotated to move the jaws axially in the respective guide passages.
The holes according to the invention can open axially rearward or radially outward. In the latter case they are L-shaped.